People who ate a daily handful of nuts were 20 percent less likely to die from any cause than those who didn't consume nuts, a U.S. study said Wednesday.
The research, published in the U.S. journal New England Journal of Medicine, also found regular nut-eaters were more slender than those who didn't eat nuts, which would alleviate the widespread worry that eating a lot of nuts will lead to overweight.
"The most obvious benefit was a reduction of 29 percent in deaths from heart disease -- the major killer of people in America, " Charles Fuchs, senior author and director of the Gastrointestinal Cancer Center at Dana-Farber Cancer Institute, an affiliate of Harvard Medical School, said in a statement.
"But we also saw a significant reduction -- 11 percent -- in the risk of dying from cancer," added Fuchs, who is also affiliated with the Channing Division of Network Medicine at Brigham and Women's Hospital.
It couldn't be determined whether any specific type of nuts was crucial to the protective effect, said the researchers. However, the reduction in mortality was similar both for peanuts and for " tree nuts" including walnuts, hazelnuts, almonds, Brazil nuts, macadamias, pecans, cashews, pistachios and pine nuts.
Several previous studies have found an association between increasing nut consumption and a lower risk of diseases such as heart disease, type 2 diabetes, colon cancer, gallstones, and diverticulitis. Higher nut consumption also has been linked to reductions in cholesterol levels, oxidative stress, inflammation, adiposity, and insulin resistance. Some small studies have linked increased nuts in the diet to lower total mortality in specific populations.
But no previous research studies had looked in such details at various levels of nut consumption and their effects on overall mortality in a large population that was followed for more than 30 years, the researchers said.
In the new research, the researchers looked at the association of nut consumption with total and cause-specific mortality among 76,464 women between 1980 and 2010 in the Nurses' Health Study and 42,498 men from 1986 to 2010 in the Health Professionals Follow-up Study.
Participants in the studies filled out detailed food questionnaires every two to four years. With each food questionnaire, participants were asked to estimate how often they consumed nuts in a serving size of one ounce. A typical small packet of peanuts from a vending machine contains one ounce (about 28 grams).
"In all these analyses, the more nuts people ate, the less likely they were to die over the 30-year follow-up period," said Ying Bao, of Brigham and Women's Hospital, the first author of the report.
Those who ate nuts less than once a week had a seven percent reduction in mortality; once a week, 11 percent reduction; two to four times per week, 13 percent reduction; five to six times per week, 15 percent reduction, and seven or more times a week, a 20 percent reduction in death rate.
The researchers noted that this large study cannot definitively prove the cause and effect but the findings are strongly consistent with "a wealth of existing observational and clinical trial data to support health benefits of nut consumption on many chronic diseases."
Nuts contain important nutrients such as unsaturated fats, high quality protein, vitamins, minerals and phytochemicals, all of which may offer cardioprotective, anticarcinogenic, anti- inflammatory and antioxidant properties.
The U.S. Food and Drug Administration concluded in 2003 that eating 1.5 ounces (about 42.5 grams) per day of most nuts "may reduce the risk of heart disease."
